Nerve Tissue
Al-Maarefa College
Nerve Tissue
• Cells have very high ability to
– Respond to stimuli
– Transmit impulses
Nerve Tissue
Nerve Tissue
• NEURON is the main nerve cell)
Nerve Tissue
• NEURON is the main nerve cell
– Cell Body(3)
– Dendrites (5)
– Axon(1)
Motor Neurone
Motor Neurone
• Cell body
• Dendrites
• Axon
– Covered by Myelin
sheath
Neuron
• Multipolar
Kuehnel, Color Atlas of Cytology, Histology, and Microscopic Anatomy
Neuron's – cerebral cortex
Kuehnel, Color Atlas of Cytology, Histology, and Microscopic Anatomy
Neuron's – spinal cord
Kuehnel, Color Atlas of Cytology, Histology, and Microscopic Anatomy
Nerve and Reflex Arc
Nerve Fiber (Axon)
• Nerve fibers are long nerve cell processes (axon
cylinder, axon) with a surrounding membrane
• Schwann cells (neurolemmocytes, peripheral glial
cells) enfold the axon and form an insulating cover
known as Schwann’s sheath (neurolemma).
Stain: osmium tetroxide; magnification: × 1000
Kuehnel, Color Atlas of Cytology, Histology, and Microscopic Anatomy
Nerve Fiber (Axon)
• Myelinated nerve fiber, i.e., the axon is covered by a
myelin sheath, which is rich in lipids.
• Every 0.8 to 1.0 mm, a node of Ranvier subdivides
the myelin sheath into segments or internodes.
Stain: osmium tetroxide; magnification: × 1000
Kuehnel, Color Atlas of Cytology, Histology, and Microscopic Anatomy
Sciatic nerve – cross section
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•
•
•
•
•
1 Fascicle (nerve fiber bundle)
2 Perineurium
3 Epineurium
4 Artery
5 Vein
6 Adipose
tissue
Stain: alum hematoxylin; magnification: × 10
Kuehnel, Color Atlas of Cytology, Histology, and Microscopic Anatomy
Glial Cells
• Glial cells (Neuroglia) or (Glia)
• (Greek "glue”
• Non-neuronal cells that:
1- maintain homeostasis,
2- form myelin,
3- provide support and protection for the brain's
neurons
• They occupy the entire space between neurons
and separate nerve cells from blood vessels
Glial Cells - Functions
1.
2.
3.
4.
Surround neurons and hold them in place
Supply nutrients and oxygen to neurons
Insulate one neuron from another
Destroy pathogens and remove dead neurons
Glial Cells - Types
• Astrocytes (macroglia)
• Oligodendrocytes
• Microgliocytes
Astrocytes
• Most abundant
• Deal with homeostasis – relate to vessels
Kuehnel, Color Atlas of Cytology, Histology, and Microscopic Anatomy
• are characteristic star-shaped glial cells in the
brain and spinal cord. They perform many
functions, including :
• 1- biochemical support of endothelial cells that
form the blood–brain barrier,
• 2- provision of nutrients to the nervous tissue,
• 3-maintenance of extracellular ion balance,
• 4- and a role in the repair and scarring process of
the brain and spinal cord following traumatic
injuries
Astrocytes and nerve cells
Kuehnel, Color Atlas of Cytology, Histology, and Microscopic Anatomy
Microglia
Microglia:
Microglia are the main resident immunological cells
the CNS
• Oligodendrocytes:
– Closely related to
neurons
– Provide myelin
protection for CNS
neurons
Neurons and glial cells
Kuehnel, Color Atlas of Cytology, Histology, and Microscopic Anatomy
Neuron and glial cells
Kuehnel, Color Atlas of Cytology, Histology, and Microscopic Anatomy
Summary
• Nerve Tissue Cells:
– Neurons:
• Myelinated
• Non-myelinated
Summary
• Nerve Tissue Cells:
– Neurons:
• Myelinated
• Non-myelintaed
– Neuroglial cells:
• Astrocytes
• Microglia
• Oligodendrocytes